In Skidmore v. Swift & Co., 323 U.S. 134, 65 S.Ct. 161, 89 L.Ed. 124 (1944), the Court awarded compensation to auxiliary firemen for their on-call shifts, during which they had to remain on or very near the employer's premises. According to the Court, resolution of the matter involved determining the degree to which the employee could engage in personal activity while subject to being called. "Facts may show that the employee was engaged to wait, or they may show that he waited to be engaged." Id. at 137, 65 S.Ct. at 163.